Circuit providing indication of air entrapment in patient's lungs

Abstract

A rate volume monitor includes a sensor which provides an output upon inspiration and upon expiration. If inspiration follows expiration too closely a computer operates an alarm to provide warning that air entrapment or "stacking" may occur in the patient's lungs.

The invention is claimed as follows: 
     
       1. Apparatus for patient ventilation comprising forced ventilation means for connection to a patient, sensor means connected to said ventilation means for producing an electrical signal in accordance with air flow on inspiration and on expiration, first signal means connected to said sensor means for detecting when expiration drops below a predetermined threshold and producing a first electrical output in accordance therewith, second signal means connected to said sensor means and producing a second electrical output upon start of inspiration, timing means to which said first and second signal means are connected and producing a third electrical output if said first and second electrical outputs are closer in time than a predetermined time, and alarm means to which said third electrical output is connected and providing an alarm if a plurality of said first and second electrical outputs are closer in time than said predetermined time. 
     
     
       2. Apparatus as set forth in claim 1 wherein said alarm means produces an additional signal, and wherein said alarm and said additional signal alternate. 
     
     
       3. Apparatus as set forth in claim 2 wherein said alarm means comprises a visual alarm means.